Apparatus and method for retrograde placement of sagittal sinus drainage catheter

ABSTRACT

A method of inserting a drainage catheter into a sagittal sinus having blood flow from an upstream to a downstream direction. A burr hole is created, if necessary, in the cranium of the patient proximate the sagittal sinus. A distal end of a catheter is inserted through the burr hole and the dura into the sagittal sinus. The distal end of the catheter is positioned so that the distal end points generally in the upstream direction with respect to the blood flow. A sagittal sinus catheter is adapted for placement through the dura of a patient proximate a superior sagittal sinus. The catheter is formed of semi-rigid material and has at least a ninety degree bend.

FIELD OF THE INVENTION

The present invention relates generally to apparatus and methods for theintroduction and placement of cranial catheters and, more particularly,to apparatus and methods for the introduction and placement of sinuscatheters.

BACKGROUND OF THE INVENTION

Ventricles of the brain contain cerebrospinal fluid (CSF) which cushionsthe brain against shock. CFS is constantly being secreted and absorbedby the body usually in equilibrium. Cerebrospinal fluid is produced inthe ventricles of the brain, where under normal conditions, it iscirculated in the subarachnoid space and reabsorbed into thebloodstream, predominantly via the arachnoids villi attached to thesuperior sagittal sinus. However, if blockages in circulation of CSF,perhaps in the ventricles, CSF can't be reabsorbed by the body at theproper rate.

This can create a condition known as hydrocephalus which is a conditionmarked by an excessive accumulation of fluid violating the cerebralventricles, then the brain and causing a separation of the cranialbones. Hydrocephalus is a condition characterized by abnormal flow,absorption or formation of cerebrospinal fluid within the ventricles ofthe brain which subsequently increases the volume and pressure of theintracranial cavity. If left untreated, the increased intracranialpressure can lead to neurological damage and may result in death.

Over the past 40 years, a common treatment for hydrocephalus patientshas been the cerebrospinal fluid shunt. The standard shunt consists ofthe ventricular catheter, a valve and a distal catheter. The excesscerebrospinal fluid is typically drained from the ventricles to asuitable cavity, most often the peritoneum or the atrium. A catheter istunneled into the brain through a burr hole in the skull. The catheteris placed into ventricles to shunt CSF to other areas of the body,principally the peritoneum, where it can be reabsorbed. The presence ofthe shunt relieves pressure from CSF on the brain.

A flow or pressure regulating valve is usually placed along the catheterpath. Differences in pressure due, at least in part, to differences invertical position between the inlet (ventricles) and the outlet(peritoneum) can create too much drainage with such a flow or pressureregulating valve.

An alternative, and newer, method to shunting CSF to the peritoneum isto shunt CSF from the ventricles to the sagittal sinus.

A conventional technique for placing a catheter in the ventricles in thebrain is to first drill a burr hole in the skull. A scalpel can then beused to create a slit in the dura surrounding the brain to gain access.However, controlling the length of the slit in the dura is difficult andwill vary from surgery to surgery.

An alternative method after first drilling a burr hole is to use cauteryto heat/burn tissue of the dura to create and opening in the dura.Still, controlling the shape and diameter of the opening in the dura isdifficult and, again, will vary from surgery to surgery.

The holes provided by the preceding techniques provide a pathway to theventricles. A catheter is then intubated into the lateral ventriclewhich remains in place in the patient.

Both standard methods of entry allow for leakage of CSF around the outersurface or diameter of the catheter from the dura post-implant. Leakageof CSF through the dura can cause serious surgical complicationsincluding infection, severe headaches and disturbances of hearing orvision. It can also lead to changes in pressures of fluid in theventricular/shunt system and result in complications and failures. Ithas been estimated that approximately forty percent (40%) of initialventricular shunt installations require correction or revision.

The shunt implantation procedure is associated with the known incidentsof complications that are recognizable and treatable. Of these,ventricular catheter obstruction is the most common reason for revisionfollowed by infection. When shunting from the ventricles to the venoussystem, either via the right auricle or the dural sinuses,thrombo-embolic complications and the dissemination of infection throughthe bloodstream are additional risks.

Shunting can also be accomplished from the ventricles to the sagittalsinus, particularly the superior sagittal sinus. This procedure involvesmaking a second entry into the cranium in order to install an outletcatheter into the sagittal sinus. Placing a distal catheter in the bloodstream of the sagittal sinus creates the potential for blood clottingand resulting occlusion of the sinus passageway.

BRIEF SUMMARY OF THE INVENTION

The present invention provides apparatus and methods for introducing andplacing a catheter placed through the dura in order to accomplish ashunting into the sagittal sinus.

In one embodiment, the present invention provides a method of insertinga drainage catheter into a sagittal sinus of a patient. The sagittalsinus has blood flow from an upstream to a downstream direction. A burrhole is created in the cranium of the patient proximate the sagittalsinus, if necessary. A distal end of a catheter is inserted through thedura into the sagittal sinus. The distal end of the catheter ispositioned so that the distal end points generally in the upstreamdirection with respect to the blood flow.

In another embodiment, the present invention provides a sagittal sinusshunt. A catheter has a ventricle portion and a sinus portion. Theventricle portion is adapted for placement into a cranium of a patientproximate a ventricle and the sinus portion is adapted for placementinto the cranium of the patient proximate a superior sagittal sinus. Avalve is operatively coupled in the catheter between the ventricleportion and the sinus portion. The sinus portion of the catheter has atleast a ninety degree bend.

In another embodiment, the present invention provides a sagittal sinuscatheter adapted for placement into said cranium of said patientproximate a superior sagittal sinus. The catheter is formed of asemi-rigid material. The catheter has at least a ninety degree bendaiding insertion in the retrograde direction and limiting the depth ofinsertion.

Positioning the discharge end of the sinus catheter in the retrogradefacing the upstream flow of blood in the sagittal sinus helps the sinuscatheter to prevent thrombosis. The collision of CSF flowing outward inan upstream direction in the sagittal sinus helps to prevent bloodflowing in the sagittal sinus from forming a wake at the discharge pointand possibly creating blood clotting conditions.

Further, the present invention is easy to use and provides importanttime savings in use by the surgeon. Minimizing surgical time providesimportant safety benefits for the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a shunt system in accordance with certainembodiments of the present invention installed in the cranium of apatient;

FIG. 2 is a side view of a ventricular catheter used in the shunt systemillustrated in FIG. 1;

FIG. 3A is a top view of a valve used in the shunt system illustrated inFIG. 1;

FIG. 3B is a side view of a valve used in the shunt system illustratedin FIG. 1;

FIG. 4 is a side view of a sinus catheter used in the shunt systemillustrated in FIG. 1;

FIG. 5 is a side view of a right angle clip used in the shunt systemillustrated in FIG. 1;

FIG. 6 is a cross-sectional view a ventricular catheter inserted into adural hole formed in accordance with embodiments of the presentinvention;

FIG. 7 is a side view of a ventricular catheter stretcher used ininstallation used of the shunt system illustrated in FIG. 1;

FIG. 8 is a side view of a female luer used in an embodiment of aventricular catheter used in the shunt system illustrated in FIG. 1;

FIG. 9 is a side view of a clamp used in installation of the shuntsystem illustrated in FIG. 1; and

FIG. 10 is a flow of a method of an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The various embodiments of the present invention can be understood byreference to the shunt system 10 illustrated in FIG. 1 which shows theventricular to sagittal sinus shunt system 10 in place in a patient 12.Ventricular catheter 14 has been inserted through a burr hole (notshown) into the lateral ventricle 16 of patient 12. Ventricular catheter14 is coupled to valve 18 which controls the flow of CSF from lateralventricle 16 to sagittal sinus 20. Valve 18 is also coupled to sinuscatheter 22 shown inserted through another burr hole (also not shown)into the superior sagittal sinus 20.

Shunt system 10 allows excess CSF present in lateral ventricle 16 toflow through ventricular catheter 14, valve 18 and sinus catheter 22into the blood stream of sagittal sinus 20 where the excess CSF can bereabsorbed into the body. The vertical distance between the location ofventricular catheter 14 and sinus catheter 22 is small compared withvertical distance usually associated with a peritoneum catheter leadingto smaller pressure differences due to gravitation between the inletcatheter, ventricular catheter 14, and the outlet catheter, sinuscatheter 22.

Blood flow in sagittal sinus 20 is generally from in the direction shownby arrow 24 from the frontal portion of cranium 26 of patient 12 to therear portion of cranium 26 of patient 12. In a preferred embodiment,distal end 28 sinus catheter 22 has a retrograde orientation in sagittalsinus 20, essentially pointing upstream against the flow of blood insagittal sinus 20 shown by blood flow arrow 24. Positioned in thismanner, outlet of CSF from distal end 28 of sinus catheter 22 provides acollision vortex in the flow of blood around sinus catheter 22. Thisretrograde position provides a substantial decrease in the likelihood ofthrombosis resulting from an ante grade position of distal end 28 ofsinus catheter 22 in the wake created by sinus catheter 22 of thebloodstream in sagittal sinus 20.

Ventricular catheter 14 is illustrated more clearly in FIG. 2 coupledwith female luer 30 (also shown in FIG. 8). Ventricular catheter 14 isan extensible elongate body having distal end 32 and proximal end 34.Distal end 32 of ventricular catheter 14 is inserted into lateralventricle 16 of cranium 26 of patient 12 as will be discussed below.Ventricular catheter 14, shown in a relaxed state, has an outsidediameter of 2.5 millimeters and a length of 15 centimeters. Ventricularcatheter 14 has a lumen with a diameter of 1.3 millimeters (relaxedstate). Distal end 32 contains outlets 36 from the lumen consisting offour rows of four holes each extending approximately 1 centimeter fromdistal end 32. Ventricular catheter 14 has 13 length markers in onecentimeter spacing from 3 centimeters to 15 centimeters from proximalend 34 including numerical length markers at 5, 10 and 15 centimeters.Such length markers aid the surgeon in determining how deeplyventricular catheter 14 is placed. Female luer 30 is sewn onto proximalend 34 of ventricular catheter 14. Ventricular catheter 14 is formed ofan extensible material such as silicone elastomer tubing having adurometer of fifty (50) and an elongation of four hundred fifty percent(450%). Ventricular catheter 14 has a tensile strength of 900 pounds persquare inch.

Valve 18 (FIG. 3A and FIG. 3B) is a one-way check valve approximately 20millimeters long, 11 millimeters wide and 4 millimeters high. Valve 18only ensure one way flow from ventricle 16 to sagittal sinus 20 anddoesn't regulate the rate of flow of CSF.

Sinus catheter 22 in FIG. 4 has distal end 28 having a smooth open-endedtip and proximal end 38. Sinus catheter 22 is formed of a semi-rigidmaterial such as silicone elastomer tubing having a durometer of eighty(80) with an outside diameter of 2.1 millimeters and a length of 25centimeters. Sinus catheter 22 has a lumen with a diameter of 1.2millimeters. Sinus catheter 22 has 23 numeric length markers in onecentimeter spacing from 3 centimeters to 25 centimeters from distal end28.

In order to properly insert sinus catheter 22 in a retrograde positionin sagittal sinus 20, sinus catheter 22 has bend 40 locatedapproximately seven (7) centimeters from distal end 28. As is shown inFIG. 1, bend 40 allows sinus catheter 22 to lie smoothly against head ofpatient 12 once inserted into sagittal sinus 20. Bend 40 actually makesit difficult for the surgeon to insert sinus catheter 22 in a positionother than retrograde essentially ensuring proper placement of sinuscatheter 22 in sagittal sinus 20. While bend 40 is illustrated to beapproximately a one-hundred eighty degree bend, other degrees of bendare possible and contemplated. Bend 40 alternatively could be a ninetydegree bend and achieve similar results. It is preferred that bend 40 beat least a ninety degree bend.

Shunt system 10 is installed by first drilling a burr hole in cranium 26using a conventional technique. In some patients, such as small childrenand/or infants, a burr hole may not be necessary. A parieto occipitalskin flap is mapped to expose the sites of sinus exposure and the duralhole for ventricular catheter 14 insertion into lateral ventricle 16.The sinus will be exposed anterior to the external occipitalprotuberance and the opening to penetrate the ventricle 16 will be madelateral and slightly anterior to the exposed sinus, in line with thelateral ventricle 16. Two separate curvilinear small incisions may beused instead of the skin flap in patients above six years of age, toaccess the superior sagittal sinus 20 and lateral ventricle 16,respectively. Alternatively, a frontal approach to access lateralventricle 16 could be used.

After reflection of the scalp, the tissue is incised over the siteschosen for the bony openings exposing the superior sagittal sinus 20 andcerebral ventricles, respectively.

The superior sagittal sinus 20 is exposed through a burr hole centeredover the sagittal suture. The burr hole may be widened to expose thesinus fully, which in some instances may deviate slightly to the rightof the sagittal suture, and bevel its posterior edge.

A burr hole may be made in line with the lateral ventricle 16, exposinga circle of dura mater. If right angle clip 42 (FIG. 5) is not used, itis recommended that the posterior rim of the burr hole be beveled wherecatheter 14 emerges and curves to lie adjacent to the skull. A subgalealpocket should be formed with appropriate depth to accept theextracranial portion of the ventricular catheter 14 and valve 18.

A burr hole will be made in skull 43 at the point of insertion ofventricular catheter 14. A hole also will be made in the dura havingpredetermined diameter as illustrated in FIG. 6. In order to helpcontrol CSF leakage cranium 26, ventricular catheter 14 is stretchedfrom its relaxed state prior to insertion through dura 44. A hole with aprecise diameter is made in dura 44 which, preferably, is approximatelythe diameter of ventricular catheter 14 in its relaxed state. In orderto be able to insert ventricular catheter 14 through dura 44,ventricular catheter 14 is stretched in a controlled manner in order toreduce its outside diameter to a diameter which is less than thecontrolled diameter of the hole made in dura 44. Ventricular catheter 14is inserted through dura 44 in its stretched state allowing easyinsertion. Following insertion, ventricular catheter 14 reverts to itsrelaxed state allowing its outside diameter to return to approximatelyequal to or smaller than its original relaxed state diameter andessentially filling the hole in dura 44. Having a controlled shape anddiameter for the hole created in dura 44 allows ventricular catheter,once inserted, to mostly fill and seal the hole in dura 44 helping toprevent or control leakage of CSF from inside cranium 26.

Catheter stretcher 46 (FIG. 7) can be utilized to controllably stretchventricular catheter 14 to a stretched state in which the outsidediameter of ventricular catheter has been made smaller to allowventricular catheter 14 to be easily inserted through a controlleddiameter hole in dura 44. Catheter stretcher 46 consists of an elongaterod having a diameter smaller than the diameter (1.3 millimeters) of thelumen of ventricular catheter 14 allowing distal end 48 to be insertedthrough female luer 30 into lumen of ventricular catheter 14. Distal end48 of catheter stretcher 46 penetrates the lumen of ventricular cathetercompletely with distal end 48 of catheter stretcher resting againstdistal end 32 of ventricular catheter 14. Curves 50 in catheterstretcher 46 make catheter stretcher 46 easier to handle. Luer cap 52 isaffixed on catheter stretcher 46 a distance away from distal end 48which is greater than the distance between distal end 32 of ventricularcatheter 14 and female luer 30. Once catheter stretcher 46 is insertedcompletely into lumen of ventricular catheter 14, female luer 30 isgrasped and pulled up and mated with luer cap 52. The amount thatdistance between distal end 48 and luer cap 52 exceeds the distancebetween distal end 32 and female luer 30 is the controlled amount whichventricular catheter 14 is stretched. As ventricular catheter 14 isstretched its outside diameter becomes smaller.

Catheter stretcher 46 also provides ventricular catheter 14 withstiffness to aid in insertion of ventricular catheter 14 into lateralventricle 16.

A small hole with a diameter greater than outer diameter of ventricularcatheter 14 in its stretched state and less than outer diameter ofventricular catheter 14 in its relaxed state is made in the center ofexposed dura mater 44.

Catheter stretcher 46 has, at its proximal end, tip 54 which is sizedand shaped at a desired diameter for the dural hole. Preferably, thisdiameter is greater than outer diameter of ventricular catheter 14 inits stretched state and less than outer diameter of ventricular catheter14 in its relaxed state. Preferably, tip 54 is hemispherically shaped.

Once the dura has been exposed, tip 54 can be applied against the duraand a diathermy current applied to catheter stretcher 46, typically bytouching a cautery needle to the shank of catheter stretcher 46 near tip54 in order to cauterize dura 44 creating a hole in dura 44 of theprecise size and shape of tip 54. Since tip 54 is sized and shaped tothe desired size and shape of the dural hole, tip 54 need not bemanipulated to manually create a hole of a size larger than a cauterytip typically used. Such undesirable manual manipulations tend to createirregular and unevenly sized holes which vary from surgery to surgery.

Right angle clip 42 on ventricular catheter 14 can be used as a markerfor planned depth of ventricular catheter 14 insertion by sliding it thedesired distance from proximal end 34 of ventricular catheter 14 priorto insertion.

Stretched ventricular catheter 14 is introduced into the lateralventricle 16 through the dural opening (the direction of ventricularcatheter insertion is along a line extending from the dural hole to theipsilateral pupil) into the anterior horn. The position of the catheterstretcher (stylet) is maintained with one hand and luer cap 52 isunlocked with the other hand allowing ventricular catheter to relax toits original diameter without retracting from ventricle 16. Ventricularcatheter 14 should fit snugly in the dural hole, helping to hermeticallyseal it. Imaging may be used to verify proper placement of the catheter.

The stylet (catheter stretcher) 46 is removed and ventricular catheteris clamped (with clamp 58 shown in FIG. 9) immediately after thewithdrawal of stylet 46 to help prevent CSF loss.

Right angle clip 42 on ventricular catheter 14 may be used to bendventricular catheter 14 to an approximate ninety degree angle where itexits the twist drill or burr hole. The extracranial portion ofventricular catheter is pressed into the split tubular segment of rightangle clip 42 to form a right angle bend. Stretching of ventricularcatheter 14 is avoided when it is pressed into right angle clip 42. Itis recommended that right angle clip 42 be secured to adjacent tissue bypassing sutures through the two suture flanges on the sides of rightangle clip 42.

A clamp is removed as necessary and saline is injected into ventricle 16through ventricular catheter 14 to replace lost CSF and to clear anytissue debris, to raise the CSF pressure and to help make sure thatthere is not leakage from around ventricular catheter 14.

The extra length of ventricular catheter 14 is cut off so that only twoto three centimeters of ventricular catheter 14 remain projectingoutward from the burr hole.

The inlet port of valve 18 is fit into the open end of ventricularcatheter 14 and is secured by a suture.

The clamp is momentarily removed on ventricular catheter 14 to primevalve 18 and to remove air bubbles. The clamp is reapplied toventricular catheter 14.

After exposing the roof of the sinus by direct observation or needlepuncture, an opening is made through the dural roof of the sinus 20large enough to accommodate sagittal sinus catheter 22. A finger isapplied on the sinus 20 at the puncture site to prevent excessive bloodloss.

Distal end 28 of sinus catheter 22 is introduced into sagittal sinus 20and advanced forward against the direction of blood flow for a distanceof approximately five centimeters. If any obstacle to the free passageof sinus catheter 22 is encountered, the sinus catheter 22 is withdrawna bit and redirected in its advance into sagittal sinus 20. Sinuscatheter 22 is advanced slightly and retracted to approximately fivecentimeters to provide additional assurance that sinus catheter 22resides in the main sagittal sinus 20 lumen.

After placement of sinus catheter 22, good blood flow is checked byallowing venous back flow into the unclamped sinus catheter 22. Afterestablishing venous back flow, saline is injected into sinus catheter 22to clear blood from sinus catheter 22. The sinus catheter 22 is clamped.Any bleeding from around sinus catheter 22 should be controlled, e.g.,by gel foam, pressure and/or suture.

The proximal end 38 of sinus catheter 22 is formed in a smooth U-curveto the outlet of valve 18. The required length of proximal end 38 ofsinus catheter 22 is estimated, the position of the clamp on sinuscatheter 22 is adjusted and the extra sinus catheter 22 is cut off.

The outlet port of valve 18 is fit into proximal end (having been cutoff) of sinus catheter 22 and secured by a suture. Valve 18 is securedby suture to the underlying pericranium.

The clamps on ventricular catheter 14 and sinus catheter are removed,respectively, allowing CSF to flow in shunt system 10. The skin isclosed in the usual manner.

A method of an embodiment of the present invention is illustrated inFIG. 10. A burr hole is created (110) in the cranium 26 of the patient12, if necessary. A catheter, such as sinus catheter 22, is inserted(112) through the dura into the sagittal sinus 20. The distal end of thecatheter 22 is positioned in a retrograde direction facing upstream tothe blood flow in the sagittal sinus 20.

The preceding specific embodiments are illustrative of the practice ofthe invention. It is to be understood, therefore, that other expedientsknown to those skilled in the art or disclosed herein, may be employedwithout departing from the invention or the scope of the appendedclaims. For example, the present invention is not limited to shuntsystems but could employed in other systems involving holes in the dura.The present invention is not limited to the apparatus described hereinper se, but may find further application in other medical areas. Thepresent invention further includes within its scope methods of makingand using the apparatus described hereinabove.

Thus, embodiments of the apparatus and method for retrograde placementof sagittal sinus drainage catheter are disclosed. One skilled in theart will appreciate that the present invention can be practiced withembodiments other than those disclosed. The disclosed embodiments arepresented for purposes of illustration and not limitation, and thepresent invention is limited only by the claims that follow.

1. A method of inserting a drainage catheter into a sagittal sinus of apatient having a cranium, said sagittal sinus having blood flow from anupstream to a downstream direction, comprising: creating a burr hole insaid cranium of said patient proximate said sagittal sinus; inserting adistal end of a catheter through said burr hole into said sagittalsinus; positioning said distal end of said catheter so that said distalend points generally in said upstream direction with respect to saidblood flow.
 2. A method of creating a sinus shunting catheter in apatient having a cranium, comprising: inserting one end of a catheterinto said proximate a ventricle of said patient; coupling a valve insaid catheter; inserting an opposite end of said catheter into saidcranium proximate a superior sagittal sinus, said superior sagittalsinus having blood flow from an upstream direction to a downstreamdirection; and positioning said catheter so that said opposite endpoints generally in said upstream direction with respect to said bloodflow.
 3. A method as in claim 2 wherein said catheter has a sinusportion between said valve and said opposite end of said catheter andwherein said sinus portion of said catheter has at least a ninety degreebend.
 4. A method as in claim 3 wherein said sinus portion of saidcatheter has approximately a one hundred eighty degree bend.
 5. A methodas in claim 4 wherein said one hundred eighty degree bend occursapproximately 7 to 11 centimeters from said opposite end of saidcatheter.
 6. A sagittal sinus shunt, comprising: a catheter having aventricle portion and a sinus portion, said ventricle portion adaptedfor placement into a cranium of a patient proximate a ventricle and saidsinus portion adapted for placement into said cranium of said patientproximate a superior sagittal sinus; and a valve operatively coupled insaid catheter between said ventricle portion and said sinus portion;said sinus portion of said catheter having approximately a one hundredeighty degree bend.
 7. A sagittal sinus shunt as in claim 6 wherein saidsinus portion of said catheter is formed of a semi-rigid material.
 8. Asagittal sinus shunt as in claim 7 wherein said sinus portion of saidcatheter has a durometer of approximately eighty (80).
 9. A sagittalsinus shunt as in claim 6 wherein said one hundred eighty degree bendoccurs approximately 7 to 11 centimeters from said opposite end of saidcatheter.
 10. A sagittal sinus shunt as in claim 6 wherein said sagittalsinus has blood flow from an upstream direction to a downstreamdirection and wherein a distal end pf said sinus portion of saidcatheter is positioned generally in said upstream direction with respectto said blood flow.